Overview

Atrial fibrillation is an abnormality of heart rhythm in which chambers of the heart contract in a disorganised manner, producing an irregular heart rate. Atrial fibrillation can lead to heart failure (shortness of breath, oedema, and palpitations) and chest pains and, when left untreated, can lead to stroke.

Normal Blood Flow in the Heart

The heart has a right side and a left side and each side has a chamber that receives blood returning to the heart (atrium) and a muscular chamber that pumps blood out of the heart (ventricle). Atria are relatively thin-walled chambers, whereas the ventricles are much more muscular. Blood passes from the atria into the ventricles through two processes. During the resting phase, when the ventricles are not contracting, the tricuspid and mitral valves open. Some of the blood that has accumulated in the atria passively flows through the tricuspid and mitral valves into the right and left ventricles, respectively. The atria then contract, pumping blood out and into the ventricles. Once the ventricles fill with blood, they contract, pumping blood into the lungs and to the body.